|Publication number||US7408944 B2|
|Application number||US 11/045,933|
|Publication date||Aug 5, 2008|
|Filing date||Jan 28, 2005|
|Priority date||Jan 28, 2005|
|Also published as||US20060209850|
|Publication number||045933, 11045933, US 7408944 B2, US 7408944B2, US-B2-7408944, US7408944 B2, US7408944B2|
|Inventors||Frank Nan Zhang, Zhicheng Hou|
|Original Assignee||Xecom, Inc.|
|Export Citation||BiBTeX, EndNote, RefMan|
|Patent Citations (7), Referenced by (2), Classifications (12), Legal Events (4)|
|External Links: USPTO, USPTO Assignment, Espacenet|
The present invention relates in general to data communication, and more particularly to a system, method, and apparatus for bridging two networks for data communication.
Modems are typically used as a means for inexpensive data communications. A modem is referred to herein as a device to connect two hosts through a data link. Modems typically convert signals produced by one type of device, e.g., a computer, to a form compatible with another device, e.g., a telephone. Many applications use modems connected to a telephone line accessible through a public switched telephone network (PSTN) to pass data to an application controller, typically a central management server. PSTN refers to the international public telephone system that carries analog voice and data signals. The term modem stands for mo(dulator)-dem(odulator) since a stream of digital data or binary bits (0's and 1's) is modulated for transmission into an analog signal within the bandwidth of the PSTN and the received analog signal is demodulated back to digital data.
Applications providing communication between different types of networks typically include a gateway device for bridging the networks. For example, one network may comprise a local wireless linked network having one or more wireless modems and the other network comprises a wired telephone line link network having one or more wired modems.
Each remote application micro-controller 12 a, 12 b typically includes a microprocessor, random access memory, non-volatile memory, and input and output signal interfaces (not shown). The remote application micro-controller 12 a, 12 b provide control based on an application program loaded therein through a loading means (not shown). The application program for each remote application micro-controller 12 a, 12 b is typically loaded as firmware stored in the non-volatile memory of the system, but is not limited to this form.
As shown in the system in
When data communication is required which is event driven or pre-scheduled, the micro-controller 12 a, 12 b typically issues commands to its connected wireless device to initiate a communication session with another wireless device. For applications using a wireless device for data communication, the controller 12 a, 12 b executes its stored application program for managing all necessary functions and for preparing reports to be forwarded to the higher level requesting application controller 30.
The application controller 30 interfaces with a wired modem 28 b via a data interface bus which is typically a serial port 26 e, as seen in
The gateway controller 24 is typically implemented using a standalone processor for managing the two different data communication devices, i.e., the wireless modem and the wired modem. The standalone processor runs a program to manage the communication between the wired and wireless links. Gateway controller 24 enables data from a wireless linked device 20 a, 20 b to be passed to a remote application controller 30 through the telephone network, i.e., PSTN. Alternatively, gateway controller 24 enables data from telephone line linked equipment, i.e. wired modems 28 a, 28 b to be passed to the wireless networked devices 20 a, 20 b, 20 c.
The standalone processor includes two serial ports for managing the two different serial ports linked devices. A program running in the processor in gateway controller 24 typically passes modem “AT” commands to the two devices for initializing the devices and to prepare each device to accept communication from either side. The modem “AT” command, also known as “the AT command set” for modems is a set of predefined commands initially developed by the Hayes Micro Computer Company in the mid 1980's to control their proprietary modem equipment used for connecting data terminals to host computing devices over the public telephone network. The AT command set is now the industry standard adopted by most modem manufacturers for controlling modems and serial data transmission over telephone lines. The AT command set has a string of characters for each command, preceded by the prefix “AT”, for sending instructions to the modem. The original AT Command set has been augmented many times as modem speeds and feature sets have increased. Special commands have been added by many vendors to control new features of their wired and wireless communication products.
The gateway controller 24 enables the wired modem 28 a and wireless modem 20 c to exchange data through the gateway if both modems are enabled to connection through the gateway controller 24 to their counterpart modem. A drawback of the system shown in
A need exists to reduce cost and device size by eliminating the separate gateway controller for bridging of two communication networks. A system, method, and apparatus are therefore needed which solves the above described drawbacks of the prior art.
The present invention provides a method and corresponding system which overcomes the drawbacks of known systems and methods.
Broadly stated, the present invention provides a system for providing a virtual host for enabling data communication between different networks the system having an application controller and comprising a wired device in a wired network coupled to the application controller via a first bus; one or more wireless devices in a wireless network, each wireless device is coupled to a corresponding host controller via a corresponding bus, the wireless devices for communicating via a corresponding wireless link; a gateway module for enabling communication between the wired network and the wireless network comprising a wired modem for communicating with said wired device via said wired network; and a wireless module coupled to the wired modem via a serial port and comprising a wireless transceiver and communications controller; wherein the gateway module enables communication between each wireless device in the wireless network and the wired device in the wired network; such that the gateway module enables communication between the host controllers and the application controller.
Broadly stated, according to another embodiment, in a system having an application controller, a wired modem in a wired network coupled to the application controller via a first serial port, one or more wireless modems in a wireless network, each wireless modem is coupled to a corresponding host controller via a corresponding serial port, the wireless modems for communicating via a corresponding wireless link, a wired device for communicating with the wired modem via the wired network, a wireless module coupled to the wired device via a second serial port for enabling communication between the wired and the wireless network and between the host controllers and the application controller comprising a wireless transceiver; a user configurable communications controller; and programmable I/O pins connected to the second serial port; and wherein the wireless module provides for the switching of direction of its serial port signals for enabling connection to the wired modem.
Broadly stated, according to another embodiment, the present invention provides a method or enabling communication between the wired and the wireless network and between the host controllers and the application controller, in a system having an application controller, a wired device in a wired network coupled to the application controller via a first serial port, one or more wireless modems in a wireless network, each wireless modem is coupled to a corresponding host controller via a corresponding serial port, the wireless modems for communicating via a corresponding wireless link, a gateway module for enabling communication between the wired network and the wireless network having a wired modem for communicating with the wired device via a wired network link and a wireless module coupled to the wired modem via a second serial port and having a wireless transceiver and communications controller; comprising the steps of initializing the wireless module for preparing the gateway module to accept communication via the wireless link; managing communication for four operating modes of the gateway module, each mode representing a different connection state of the wired modem and the wireless module comprising managing communication for a first mode wherein the wired modem is not connected to the application controller and the wireless modem is not connected to one of the host controllers; managing communication for a second mode wherein the wired modem is connected to the application controller and the wireless module is not connected to one of the host controllers; managing communication for a third mode wherein the wireless modem is connected to one of the host controllers and the wired modem is not connected to the application controller; managing communication for a fourth mode wherein the wired modem is connected to one of the application controller and the wireless modem is connected to the host controller; selectively switching between the modes as a function of the connection state of the wired modem and the wireless module; responsive to a predetermined command transmitted from one of the wireless modems, selectively enabling the commanding wireless modem to communicate with the wired modem through the gateway module; and responsive to a predetermined command transmitted from the wired device, selectively enabling the wired device to communicate with the wireless module through the gateway module.
An advantage of the present invention is that it eliminates the need for a separate application microcontroller in a gateway application. In a preferred embodiment, the present invention enables direct connection of a wired modem to a wireless modem having a transceiver and a communications controller. The present invention enables management and control capabilities to be embedded into the communications controller of the wireless device so as to enable direct connection from the wireless device to the wired modem, eliminating the separate gateway controller. In other words, the present invention enables a single controller in the wireless device to manage wireless communication and modem operation so as to eliminate the gateway controller. As a result, equipment cost is reduced because there is no need for a separate gateway controller for bridging two networks.
These and other embodiments, features, aspects, and advantages of the invention will become better understood with regard to the following description, appended claims and accompanying drawings.
The foregoing aspects and the attendant advantages of the present invention will become more readily appreciated by reference to the following detailed description, when taken in conjunction with the accompanying drawings, wherein:
Reference symbols or names are used in the Figures to indicate certain components, aspects or features shown therein, with reference symbols common to more than one Figure indicating like components, aspects or features shown therein.
The present invention will now be described in more detail with reference to
Wireless virtual host modem 120 replaces the wireless modem 20 c and the gateway controller 24. According to an embodiment of the present invention, devices coupled to either side of gateway 102, i.e., the PSTN 18 or the wireless links 16 a, 16 b, can send AT commands to a modem on either side of gateway 102. The present invention provides a pass-through function wherein a remote device, e.g., wireless modem 20 a, can send AT commands to a modem on the other side of gateway 102, e.g., wired modem 28 a. For this example, the system 100 enables a wireless networked device 20 a to first make a call to the wireless virtual host modem 120 that provides the gateway and connect to it. The system then enables the remote wireless modem, e.g., 20 a, 20 b, to send AT commands to the wired modem 28 a to control it. The remote wireless modem can control wired modem 28 a to call wired modem 28 b linked to the application controller 30 in order to make a connection to the application controller 30. According to this example, the pass-through function in wireless virtual host modem 120 enables a gateway connection for enabling a remote wireless modem, e.g., 20 a, 20 b, to communicate with the application controller 30. In this example, the gateway linked path for communication is via a linked path that includes gateway 102, wired modem 28 b, and serial port 26 e to application controller 30. More specifically, the path from wireless modem 20 a, 20 b includes the wireless link 16 a, 16 b to wireless virtual host modem 120, serial port 126, wired modem 287 a, wired device 28 b, serial port 26 e, and application controller 30. Thus, wired devices connected to gateway 102 can communicate when both sides of gateway 102, i.e., wired modem 28 a and wireless virtual host modem 120, are connected.
The initialization of the virtual host 120 prepares the gateway 102 to accept remote calls via a wireless link. An AT command ATSO=1 sent to a modem in gateway 102 will direct it to connect automatically when it receives a call.
The pass-through function is implemented in the firmware in the wireless virtual host modem 120. The pass-through function according to the present invention enables a connected remote host to gain control of a modem on one side of the gateway 102 by calling the other side of the gateway 102, i.e., either the wired modem 28 a or wireless virtual host modem 120, from a remote counterpart host and making the connection. For example, the present invention enables a micro-controller 12 a to send AT commands to the wired modem 28 a of the gateway 102 for controlling modem 28 a if the wireless virtual host modem 120 of the gateway 102 has connected with the micro-controller 12 a. The present invention enables two host controllers in two different networks, e.g., application controller 30 and micro-controller 12 a in
A modem device typically has a serial port to communicate with a host computer or host controller. Devices which use serial ports for their communication are split into two equipment categories. The modem has been defined as a Data Communication Equipment (DCE) and the host computer or host controller is defined as a Data Terminal Equipment (DTE). In a standard serial port, signals are defined either ways. Table 1 shows a description and designation for an RS-232 standard serial port signal set having 9 signals/pins.
Data Carrier Detect
DTE enable DCE to send
DCE enable DTE to send
A modem is typically a Data Communication Equipment (“DCE”) device. The serial port signals for the wireless virtual host modem 120, however, must be changeable so that the modem functions like a DTE device since for communication for the virtual host function the wireless virtual host modem 120 is connected directly to the wired modem 28 a via serial port 126, rather than being connected to wired modem 28 a through the gateway controller 24. According to this connection for the virtual host function, the wireless virtual host modem 120 functions as a DTE and the wired modem 28 a as a DCE. For example, for the pass-through function, a remote calling party will see “through” the wired link and see the AT command interface of the wireless virtual host modem 120 if the remote calling party calls wired modem 28 a and gets connected thereto. Thus, the pass-through function of the present invention enables wired modem 28 a to control the wireless virtual host modem 120 in order to connect to another wireless modem device, e.g., wireless modem 20 a.
The wireless virtual host modem 120 must provides for switching its serial port signal direction from its DCE status to DTE status to enable connection to another wired modem device (DCE). According to the present invention, wireless virtual host modem 120 is software configurable and includes programmable I/O pins for providing the switching. For enabling the virtual host function of wireless virtual host modem 120, all of its serial port signals reverse directions so as to change the serial port signals, i.e., in Table 1, of wireless virtual host modem 120 from DCE to DTE without changing the signal names.
The main virtual host functions of wireless virtual host modem 120, other than serial port signal management and control, are provided through software as will be described in further detail below. The virtual host function of wireless virtual host modem 120 is provided through control of its initialization to configure its serial port as DTE's along with management and controls of four operational modes.
The four operational modes of the wireless virtual host modem 120 according to the embodiment of system, method, and apparatus of the present invention shown in
Turning to further details of the specific process steps for the process 140 for Mode 01 shown in
Turning to further details of the specific process steps for the process 150 for Mode 10 shown in
Turning to further details of the specific process steps for the process 160 for Mode 11 shown in
According to an embodiment of the present invention, when filtering for the “DISCONNECT” or “NO CARRIER” string from the serial port input, the system, apparatus, and method includes detection of hardware signals, e.g., the DCD signal in Table 1, for determining if the connection has been lost.
Having disclosed exemplary embodiments, modifications and variations may be made to the disclosed embodiments while remaining within the scope of the invention as described by the following claims.
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|U.S. Classification||370/401, 455/557, 370/338, 370/352|
|International Classification||H04L12/28, H04W88/16, H04W92/02|
|Cooperative Classification||H04M11/06, H04W92/02, H04W88/16|
|European Classification||H04W92/02, H04M11/06|
|Sep 14, 2005||AS||Assignment|
Owner name: XECOM, INC., CALIFORNIA
Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:ZHANG, FRANK NAN;HOU, ZHICHENG;REEL/FRAME:016538/0567;SIGNING DATES FROM 20050727 TO 20050801
|Mar 19, 2012||REMI||Maintenance fee reminder mailed|
|Aug 5, 2012||LAPS||Lapse for failure to pay maintenance fees|
|Sep 25, 2012||FP||Expired due to failure to pay maintenance fee|
Effective date: 20120805